Multi-track turret and overload protection

ABSTRACT

A punch press is provided with turrets having radially spaced tools and a radially shiftable striker for selectively engaging the tools. The striker is carried by a transport mechanism which is shifted by powered means and is vertically slideable relative to the powered means. The powered means include two radially spaced cylinders each containing a piston. A fixed piston rod is connected to the radially inner piston and a moveable piston rod is connected to the radially outer piston and to the transport means. Accurate positioning of the striker is obtained by controlling the relative positions of the pistons and cylinders. The transport means holds the striker for free relative upward movement. A shear plate is positioned over the striker and a backup plate is positioned over the shear plate. The backup plate contains openings for receiving a slug cut from the shear plate by the striker to relieve the striker when overloaded.

United States Patent 1 Daniels [15] 3,685,380 [451 Aug. 22, 1972 [54] MULTI-TRACK TURRET AND OVERLOAD PROTECTION [72] Inventor: Dennis Daniels, Williamsville, NY. [73] Assignee: U.S. Amada, Ltd., Seattle, Wash. [22] Filed: Feb. 19, 1971 [21] Appl. No.: 113,043

[52] US. Cl. ..83/552, 408/35, 83/534 [51] Int. Cl. ..B26d 5/08 [58] Field of Search ...83/552, 618, 214, 534; 408/35 [56] References Cited UNITED STATES PATENTS 4/1942 l-lagerstrom et al. ..83/552 10/1970 Offenstadt ..83/534 Primary Examiner-Willie G. Abercrombie Attorney-Seed, Berry & Dowrey [57] ABSTRACT A punch press is provided with turrets having radially spaced tools and a radially shiftable striker for selectively engaging the tools. The striker is carried by a transport mechanism which is shifted by powered means and is vertically slideable relative to the powered means. The powered means include two radially spaced cylinders each containing a piston. A fixed piston rod is connected to the radially inner piston and a moveable piston rod is connected to the radially outer piston and to the transport means. Accurate positioning of the striker is obtained by controlling the relative positions of the pistons and cylinders. The transport means holds the striker for free relative upward movement. A shear plate is positioned over the striker and a backup plate is positioned over the shear plate. The backup plate contains openings for receiving a slug cut from the shear plate by the striker to relieve the striker when overloaded.

5 Clains, 3 Drawing Figures PATENTEDmsez I972 3,685,380

FIG 3 I INVENTOR. DENNIS DANIELS ATTORNEYS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to punch presses and particularly to turret type punch presses.

2. Description of the Prior Art Heretofore the maximum number of tools that given turrets could carry was limited by the size and number of tools which could be placed on a single radial track around the turret axis of rotation. The common practice being that all tools were presented below a punching striker at a fixed radial distance from the turret axis. As a result the use of the machine was limited. In addition the radial distance of the single track from the turret axis was determined by the size of the largest tool to be carried on the turret and thus space was wasted between the smaller tools on the track and the periphery of the turret.

A second difficulty in prior art punch presses was that the striker was not provided with an adequate overload mechanism frequently causing damage to the striker or the tool or both when an overload occurred.

SUMMARY OF THE INVENTION It is an object of this invention to increase the number of tools that can be carried on a punch press turret.

It is another object of this invention to provide a turret for a punch press wherein the tools maybe spaced close to the periphery of the turret.

It is another object of this invention to provide a punch press wherein the striker is radially shiftable to engage tools radially spaced from a turret axis.

It is another object of this invention to provide a radially shiftable striker having an overload release to prevent damage when an overload occurs in any of the strikers shiftable positions.

It is another object of this invention to provide an overload mechanism for a conventional single track turret.

Basically the multi-track feature includes upper and lower turrets carrying tools such as a punch and die. At least one tool is spaced at a difierent radial distance from another. Means is provided for shifting the striker radially to position it above the radially spaced tool. In the preferred embodiment the striker is shifted by unique piston and cylinder powered means.

The radial spacing of the tools provides for aligning several smaller tools at radially different distances from the central axis of the turrets to increase the number of tools on the turrets. A further advantage is that a tool may be positioned much closer to the periphery of the turrets allowing for considerably less interference to the work piece holding means and permitting greater work area coverage.

The means for overload protection is incorporated in the shifting punch striker but may also be employed for a non-shiftable striker. Basically the overload protection means includes means for holding the striker for free upward movement, a shear plate positioned over the striker, 6 a backup plate positioned over the shear plate, the backup plate having apertures for receiving a slug cut from the shear plate whereby the punching load over a safe maximum will drive the striker into the 2 shear plate for allowing upward movement of the striker relative to the ram.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of a punch press embodying the principles of the invention.

FIG. 2 is a fragmentary vertical section taken through a portion of the punch press shown in FIG. 1.

FIG. 3 is a fragmentary plan of the top turret shown in FIG. 2

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a conventional C-frame punch press 10 housing a work-piece holder 12 and workpiece positioning means 14.

The punch press '10 carries turret mechanism 15 and ram 16 embodying the principles of the invention. The turret mechanism 15 includes upper and lower turrets 20 and 22 keyed to shafts 18 and 19 for rotation about a central axis 17. The turrets contain a plurality of tools, such as punches 23, at least some of which are radially spaced along tracks A, B and C. As is readily apparent a substantially larger number of tools may be positioned on the turrets. For example, a typical installation could utilize more than 30 additional tools. Furthermore, even individual small tools may be positioned on track C further out from the central axis 17 than the larger tools which are required by their size to be positioned on an inner track.

The lower turret 22 is provided with the remaining portion of the tools, such as dies 25, aligned respectively below the corresponding punches 23. Thus the dies 25 are also spaced on tracks that are spaced in radially varying distances from the central axis 17.

The ram 16 includes a conventional eccentric 30 connected in conventional means to a ram body 32 which is mounted for slidable vertical movement in the punch press frame. The ram body is provided with radially spaced recesses 34 corresponding to the radially spaced tracks A, B and C of the turret mechanism 15. A backup plate of hard material is positioned adjacent the ram body and is provided with apertures in alignment with the recesses 34. A shear plate 38 of inexpensive material is readily replaceably positioned against the backup plate 35 and is of a material which will shear at some predetermined stress less than the overload limit of the press.

The ram body 32 is provided with a guide 40 which slidably receives a transport member 42. The transport member slidably receives a striker 44 having an enlarged head to allow the transport member to support the striker while still allowing the striker to move vertically upward relative thereto. Thus it is readily apparent that when the striker 44 is positioned below one of the apertures 36 and above the corresponding tool on the turrets an overload will drive the striker up relative to the transport member 42 pushing a slug from the shear plate 38 into the aperture of the backup plate. In

, other words, the striker, shear plate, and backup plate act much like an inverted punch and die.

The means for radially shifting the striker 44 includes powered means 48. The powered means includes two radially spaced cylinders 49 and 50 separated by a block 51. A piston 52 is slidably received in the cylinder 49 and is fixed to a rigidly mounted piston rod 54. A piston 56 is slidably received in the cylinder 50 and is secured to a movable piston rod 58. The movable piston rod 58 is secured to a coupling 60 that is connected to the transport member 42 to move the transport member radially but allow relative vertical movement between the coupling and the transport member. Suitable control means 62, the details of which are readily apparent to one skilled in the art, are coupled by pneumatic lines to ports 63 provided in each of the cylinders.

While the preferred form of the invention has been illustrated and described, it should be understood that the details are capable of being modified by one skilled in the art without departing from the principles of the invention. Accordingly, the invention is to be limited only by literal interpretation of the claims appended hereto.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A punch press having multi-track turret mechanism rotatable about a central axis, said turret mechanism including upper and lower turrets for holding a plurality of circumferentially spaced tools some of which are at different radial distances from said central axis, means for rotating said turrets into selected positions, a punch striker, means for selectively shifting the striker radially over the radially spaced tools, and means for driving said striker against the tool in any one of said shifted positions.

2. The punch press of claim 1 said means for shifting the striker including transport means for holding the striker, powered means for shifting the transport means radially, and means for securing the transport means to the powered means for allowing relative vertical motion therebetween so that the striker can be driven downwardly against the tool.

3. The punch press of claim 2 said powered means including a ram having at least two radially spaced cylinders, a piston in each cylinder, a fixed piston rod secured to the radially inner cylinder, a movable piston rod secured to the radially outer piston and to said transport means, and control means for directing pressurized fluid into selected cylinders for shifting the piston'rods and cylinders relative to one another for shifting the transport radially into predetermined positrons.

4. The punch press of claim 1 said means for driving the striker including a backup plate having apertures aligned with the radial positions of the shiftable striker, a shear plate positioned between the striker and the backup plate, said striker shifting means including means for holding the striker for free upward movement whereby an overload will drive the striker up through the shear plate.

5. A punch press having a punch striker, a ram for driving the striker downwardly, means aligned below the striker for holding a tool, means for holding the striker for free upward movement, a shear plate positioned over said striker, a backup plate positioned over said shear plate, said backup plate having at least one opening for receiving a slug cut from said shear plate whereby a punching load over a safe maximum will drive the striker into the shear plate for allowing upward movement of the sirik er rglative to the ram. 

1. A punch press having multi-track turret mechanism rotatable about a central axis, said turret mechanism including upper and lower turrets for holding a plurality of circumferentially spaced tools some of which are at different radial distances from said central axis, means for rotating said turrets into selected positions, a punch striker, means for selectively shifting the striker radially over the radially spaced tools, and means for driving said striker against the tool in any one of said shifted positions.
 2. The punch press of claim 1 said means for shifting the striker including transport means for holding the striker, powered means for shifting the transport means radially, and means for securing the transport means to the powered means for allowing relative vertical motion therebetween so that the striker can be driven downwardly against the tool.
 3. The punch press of claim 2 said powered means including a ram having at least two radially spaced cylinders, a piston in each cylinder, a fixed piston rod secured to the radially inner cylinder, a movable piston rod secured to the radially outer piston and to said transport means, and control means for directing pressurized fluid into selected cylinders for shifting the piston rods and cylinders relative to one another for shifting the transport radially into predetermined positions.
 4. The punch press of claim 1 said means for driving the striker including a backup plate having apertures aligned with the radial positions of the shiftable striker, a shear plate positioned between the striker and the backup plate, said striker shifting means including means for holding the striker for free upward movement whereby an overload will drive the striker up through the shear plate.
 5. A punch press having a punch striker, a ram for driving the striker downwardly, means aligned below the striker for holding a tool, means for holding the striker for free upward movement, a shear plate positioned over said striker, a backup plate positioned over said shear plate, said backup plate having at least one opening for receiving a slug cut from said shear plate whereby a punching load over a safe maximum will drive the striker into the shear plate for allowing upward movement of the striker relative to the ram. 